Filament reinforced tapes useful as underwater pipe wrap

ABSTRACT

A pressure-sensitive tape comprising a backing, a layer of corrosion-resistant filaments on one surface of the backing, and pressure-sensitive adhesive layer that coats the filaments and binds them to the backing. A method for constructing a member for undersea deployment is provided, which comprises providing at least one tubular member, winding a wire reinforcement about the tubular member(s); and winding a corrosion-resistant filament-reinforced material over the wire reinforcement; and coating the filament reinforced member(s) with a layer of extruded polymer.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/847,223 filed Sep. 26, 2006, and U.S. Provisional Application No.60/847,637 filed Sep. 27, 2006, the contents of which are herebyincorporated by reference.

BACKGROUND OF INVENTION

This disclosure relates to reinforcing materials that are useful in themanufacture of pipes, rods, conduits and conduit bundles for underseadeployment, and the wrapping of pipes, rods, conduits and conduitbundles with these materials.

Filament reinforced tapes have been used in the construction of underseaconduit or in the assembly of conduit bundles. For purposes of thisdisclosure, the term “conduit” may be understood to broadly refer to anytube for transporting one or more utilities such as natural gas, oil,water, electrical cable, optical filament, phone cable, and the like.The term “tubular member” is used herein to more broadly refer totubular members such as pipes and rods, as well as conduits. In a moreparticular example, the conduit may be an unbonded, flexible,continuous, spoolable tube. One tape that has been used for this purposeis a glass filament reinforced tape available commercially from 3MCompany under the designation Scotch 890 Filament tape. This tape isadvertised as having an initial tensile strength of 600 lb/in width, butwhen tested in sea water at up to 70° C. its strength degrades rapidlyand it is not desirable for long term, e.g., 25 year service life,undersea applications.

U.S. Pat. No. 6,641,330 illustrates one application offilament-reinforced tapes to undersea conduit wherein a plurality ofundersea conduits are bound together using filament-reinforced tapes asthe conduits are payed out and laid at sea. Scotch glassfilament-reinforced tape 8981 is disclosed as being suitable for thispurpose. In another application, filament-reinforced tapes have beenused in the construction of undersea conduit to provide afilament-reinforced inner layer that is used to bind metal wire or bandreinforcements that are wound around an intermediate polymeric tube thatis fabricated during the manufacturing process. However, for each ofthese applications, it is desired that the filament-reinforced taperetain its properties for up to 25 years when the tape is deployed underseawater. In particular, this means that the tape should be resistant tohigh external pressures at depths up to 3,000 meters and resist thecorrosive effects of seawater.

Accordingly, there is a need for a flexible filament-reinforced materialor pressure sensitive adhesive tape for building and/or wrapping orbinding undersea conduit.

SUMMARY OF THE INVENTION

One embodiment of the invention is a tape that includes a backing, alayer of corrosion-resistant filaments on one surface of the backing,and a pressure sensitive adhesive layer coating the filaments andbinding them to the backing. In accordance with the invention, thereinforcing filaments are selected from E-CR, S, E and AR glassfilaments, coated glass filaments, ultra high molecular weight (UHMW)polyethylene filaments, UHMW polypropylene filaments, aramid filaments,liquid crystalline polymer (LCP) filament, carbon filament, andcombinations thereof. LCP filament is a wholly aromatic liquid crystalpolyester filament. One example is 6-naphthalene carboxylic acid,6-(acetyloxy)-polymer with 4-(acetyloxy)benzoic acid (CAS# 70679-92-4),which is commercially available as VECTRAN™.

In another embodiment of the invention, a method is provided, whichcomprises: providing at least one tubular member, winding a wirereinforcement about the tubular member, and winding afilament-reinforced material or pressure sensitive adhesive tape asdisclosed herein over the wire reinforcement, and coating the filamentreinforced tubular member with a layer of extruded polymer. In a moreparticular embodiment, the tubular member(s) is/are conduit(s).

In a further embodiment, the reinforced pressure-sensitive tapesdescribed herein may be used to splice two conduits together.

In accordance with another embodiment of the invention, a method ofbinding a plurality of tubular members is provided comprising the stepsof: providing a plurality of tubular members, and wrapping the pluralityof tubular members with a filament reinforced material or tape, thefilament reinforcement being selected from the group consisting of E-CR,S, E and AR glass filaments, coated glass filaments, UHMW polyethylenefilaments, UHMW polypropylene filaments, aramid filaments, liquidcrystalline polymer (LCP) filament, carbon filament, and combinationsthereof. In a more particular embodiment, the tubular member(s) is/areconduit(s). In accordance with another embodiment of the invention, thismethod is carried out on a sea-going vessel and the method additionallyincludes the step of laying the wrapped conduits in the sea by advancingthe conduits from the vessel.

In accordance with one particular embodiment, the filament is a whollyaromatic LCP filament, and, more particularly VECTRAN™.

DETAILED DESCRIPTION

One embodiment of the invention is a filament-reinforced tape for use inthe manufacture, wrapping and/or bundling of tubular member(s) and, moreparticularly, conduit(s) for deployment undersea, which comprises: acarrier, a layer of filament reinforcement such as E-CR, S, E and ARglass filaments, coated glass filaments, UHMW polyethylene filamentssuch as those commercially available as Spectra and Dyneema filamentsand fibers, UHMW polypropylene filaments, aramid filaments such as thosecommercially available as Kevlar, liquid crystalline polymer (LCP)filament, carbon filament, and combinations thereof, and apressure-sensitive adhesive layer that binds the filament reinforcementsto the carrier. A release coating or liner is used to produce aself-wound product in the case of a pressure sensitive tape.

The carrier utilized in the tapes may be any suitable polymeric film,paper, woven or non-woven material of the type encountered in tapeproducts. Representative polymeric film examples may include, but arenot limited to: polyethylene, polypropylene, polyamides, celluloseacetate, copolymers of vinyl chloride and vinyl acetate, polyvinylchloride, polyvinylidene chloride, polyvinyl butyral, polystyrene,polytrifluorochloroethylene, synthetic rubbers such as butadiene-styreneand ABS polymers, mono or biaxially oriented polypropylene films,polyester, PVC, blends of any of the above polymers, release and otherfilms, as well as foamed materials, wovens, knits, and nonwovens in webform. In a particular embodiment, polyethyleneteraphthalate (PET) isused. Any grade conventionally employed in the production ofpressure-sensitive tapes is acceptable.

Pressure sensitive adhesives (PSA) useful in certain embodiments of theinvention include polymeric-based adhesives. PSA's include, but are notlimited to, PSA's derived from acrylic, silicone, synthetic rubber,natural rubber and modified acrylic formulations. Several commontechniques are used for manufacturing PSA's including solvent-based,hot-melt and emulsion processes. In solvent-based fabrication, theadhesive ingredients are polymerized, dissolved or dispersed in solventand cast onto a web. After the adhesive is deposited on the carrier ortransfer substrate, the solvent is dried, leaving behind the functionaladhesive. Hot-melt processing typically involves thermoplastic rubbersformulated with tackifying resins, oils and antioxidants. The hot meltadhesive is deposited on the carrier or transfer substrate at very hightemperatures (greater than about 300° F.) and solidifies prior to beingwound in the roll. Emulsion techniques use adhesive ingredients that arepolymerized in water deposited on the carrier or transfer substrate andthen dried. In one embodiment the coated adhesive composition may becrosslinked with the aid of electron beams or UV energy in a mannerknown in the art. For example, crosslinking the adhesive using UV energyrequires the addition of appropriate UV promoters (e.g.,photoinitiators, such as peroxides).

Any known coating technique can be used to apply the adhesive. Slot-diecoating, roll-over-roll, knife-over-roll, curtain and calenderingprocesses are examples of techniques that can be used.

In another embodiment, the reinforcement is used in the form of a band,scrim, strap, or cloth. The reinforcement may deploy the reinforcingfibers disclosed herein bidirectionally or unidirectionally.Combinations of reinforcing fibers may be used in any reinforcement orcombinations of reinforcing fibers and fibers that are not necessarilyreinforcing but function to bind the reinforcement together. Forexample, a scrim may be prepared having VECTRAN™ filament running in thewarp direction and cotton or nylon filament may run in the weftdirection. These reinforcements may be incorporated into apressure-sensitive tape. Alternatively, the reinforcement may be wrappedor wound directly around the tubular member(s) or conduit withoutincorporating into a tape and the tubular member(s) or conduit(s) may becoated with one or more extruded polymer covering layers. In anotherembodiment, the reinforcement filament may be formed into a fiber andwrapped or wound around the tubular member(s) or conduit(s) directly.

One filament that is particularly desirable for use in one embodiment ofthe invention is a filament that is essentially free of atomic elementsor molecular species that may weaken or may be leached out in thepresence of seawater thereby weakening the reinforcing character of thefilament over time. One example of such is ultra high molecular weightolefin filaments. These filaments are characterized in that it isessentially free of boron and fluorides and it is resistant to theleaching of metallic ions such as calcium and magnesium ions byseawater. UHMW olefin filaments useful in the invention are commerciallyavailable from Honeywell and DSM.

Carbon filaments are useful in another embodiment of the invention.Carbon is substantially resistant to alkali. Carbon filaments areavailable from Toray.

In another embodiment of the invention, LCP filaments are used. VECTRAN™is a high performance multi-filament yarn spun from liquid crystalpolymer (LCP), a wholly aromatic polyester, and exhibits exceptionalstrength and rigidity. VECTRAN™ filament is supplied by Kuraray America,Inc. VECTRAN™ is a co-polymer of p-hydroxybenzoic acid and a 6hydroxy-2-naphthoic acid. VECTRAN™ is available in 200 to 1500 denier.It is available as an untwisted filament or a filament twisted up to 2.5times per inch. Any of these commercially available filaments can beused in accordance with this disclosure.

Coated filaments are long, thin, flexible filaments made of glass (e.g.,E-glass), carbon, plastic or the like, wherein the filament is coated,covered, or impregnated with protective materials, such as but notlimited to lacquer, varnish, rubber, or polymers. In one embodiment ofthis invention, typical coatings suitable for producing a coatedfilament may contain compositions such as epoxy-polyamide (epoxies),isocyanate-amine (polyureas), isocyanate-polyol (polyurethanes),acrylate copolymer (cyanoacrylates) and polyol-acid (polyesters). Thesecoatings may be used in conjunction with any of the filaments discussedabove to improve corrosion resistance where the corrosion resistance ofthe filament itself is not suitable. The coatings must be flexible anduniformly applied over the filaments so that, in the winding of thetape, they do not become discontinuous and therefore ineffective. If thecoating continuity is compromized, the filaments will be exposed tocorrosive agents. In one embodiment, glass is coated with a polymericcoating. In another embodiment E-glass is coated with a polymericcoating. Our particular coating is sold under the name Genflo3000, acarboxylated styrene butadiene latex available from Omnova Solutions,Inc.

In accordance with a further embodiment of the invention, combinationsof any of the aforementioned filaments may be used in the reinforcingmaterial or tape. In particular, in accordance with one embodiment ofthe invention, E-glass can be warped with E-CR glass filaments.Similarly, E-glass filaments can be warped with AR glass filaments. Inaccordance with still another embodiment of the invention, E-glassfilaments can be warped with S-2 glass, carbon glass, VECTRAN™, and/orSpectra filaments. While the E-glass filaments are not as corrosionresistant as the other filaments mentioned above, there may be costadvantages in some applications to using the E-glass filament, which isgenerally less expensive than the ECR filament. When using filaments incombination in accordance with this embodiment of the invention, thefilaments may be used in any suitable orientation. For example, onefilament may be oriented parallel the tape while another filament may beoriented perpendicular to the tape, mixtures of both filaments may beoriented parallel and perpendicular to the tape and the filaments mayalso be oriented at any angle between parallel and orthogonal.

The filaments will be incorporated in the tape in an amount thatprovides the desired strength characteristics, e.g., tensile strength.Commercially available denier or diameter filaments can be used. In oneembodiment, the filaments are oriented in a direction parallel thelength of the tape. However, they can be oriented in the crossdirection, in the cross-wise and length-wise direction as in scrims,cloths and composites, or at any angle that is suitable to the purpose.A random orientation may also be acceptable in some applications. Toincrease tensile strength, the filaments may be twisted. For example,untwisted 1500 denier VECTRAN™ filament has an average 81 lb/strandtensile strength while a 1500 denier VECTRAN™ filament that is twisted1.5 times per inch (TWI) has an average 89 lb/in tensile strength. TheVECTRAN™ filaments may be used in amounts of 10 EPI or greater, moreparticularly 20 EPI or greater.

In accordance with a further embodiment, the invention provides a methodfor bundling tubular member(s) or conduit(s) for undersea applications.In accordance with this invention, tubular member(s) or conduit(s) arewrapped in one or more layers of filament-reinforced tapes and/or band,cloth, or fiber reinforcements as described herein. These tapes andreinforcing materials may be wrapped in one or more layers that maypartially or substantially overlap. In a particular embodiment, twofilament-reinforced tapes are wrapped around the bundled members inopposite directions such that the reinforcing filaments in therespective tapes cross and thereby strengthen the bundled product.Similar techniques can be used in manufacturing conduit usingfilament-reinforced tapes and reinforcing materials in accordance withthe invention. That is, the filament-reinforced tape can be wrappedaround the conduit intermediate. The tape may partially or substantiallycompletely overlap or, in another embodiment, two tapes may be wrappedaround the intermediate in opposite directions (or a plurality ofdifferent orientations) such that the reinforcing filaments cross. Thenumber of layers will depend upon the amount of filament incorporatedinto the tape and the strength/tensile characteristics desired in thefinal product.

The reinforced conduit is typically covered with one or more polymercoatings. These coatings are typically extruded over the reinforcedconduit. Examples of the extruded coverings are known in the art andinclude polymers such as HDPE, PVDF, etc.

EXAMPLE

In accordance with one non-limiting example, a tape is prepared using a92 gauge polyester backing, 1500 denier twisted VECTRAN filamentsoriented parallel the length of the tape. The filaments are adhered tothe backing by application of a crosslinked natural rubber adhesive. Inmore detail, the filaments are assembled with the PET backing and theassembly is coated with a laminating layer of adhesive. In this example,the laminating adhesive is a NR base, 40% solids, applied at a coverageof 16 lbs/ream. The laminating adhesive is dried and the tape is coatedwith a topcoat adhesive. In this example, the topcoat was applied in twocoats. Each coat was the same 40% solids NR adhesive used in thelaminating process but applied in an amount of 21 lbs/ream for a totaltopcoat adhesive coating of 42 lbs/ream. The release coat was thenapplied to the opposite side of the PET backing as a 1% solids coatingin a dry weight of 0.02 lbs/ream. The release layer used in this exampleis a Quilon (QBX) release agent. In accordance with one embodiment atape as described in this example was made using 14 EPI (ends per inch)VECTRAN™ filaments. In another embodiment a tape as described herein wasmade using 21 EPI VECTRAN™ filaments. The 14 EPI tape had an initialtensile strength of 1000 lb/in. The 21 EPI tape had an initial tensilestrength of 1800 lb/in. Both tapes were tested in 70° C. seawater undera static load to construct a log time—log load regression curve forextrapolating the 25 year tape strength. The testing showed that the 14EPI tape retained 414 lbs/in load strength over 25 years and the 21 EPItape retained 625 lb/in load strength.

Having described the invention in detail and by reference to specificembodiments thereof, it will be apparent that numerous modifications arepossible without departing from the spirit and scope of the followingclaims.

1. A pressure-sensitive tape comprising a backing, a layer ofcorrosion-resistant filaments on one surface of the backing, andpressure-sensitive adhesive layer that coats the filaments and bindsthem to the backing.
 2. The tape of claim 1 wherein thecorrosion-resistant filaments are resistant to sea water.
 3. The tape ofclaim 2 wherein the filaments are selected from the group consisting ofE-CR filament, AR glass filament, S glass filament, E glass filament,LCP filament, aramid filament, UHMW polyethylene or polypropylenefilaments, carbon filament, coated filament, and combinations thereof.4. The tape of claim 3 wherein the filament is an LCP filament.
 5. Thetape of claim 4 wherein the LCP filament is a filament of polyester of2-naphthalene-6-carboxylic acid and 4-hydroxy benzoic acid.
 6. The tapeof claim 5 additionally including a release layer on the surface of thebacking opposite the filaments.
 7. The tape of claim 1 wherein the tapeis constructed such that it provides an initial tensile strengths of atleast 1000 lb/in.
 8. The tape of claim 7 wherein the tape is constructedsuch that it provides an initial tensile strength of at least 1500lb/in.
 9. The tape of claim 8 wherein the tape provides an initialtensile strength of at least 1800 lb/in.
 10. The tape of claim 4 whereinthe filaments are twisted.
 11. The tape of claim 4 wherein the filamentshave a denier of about 200 to
 1500. 12. The tape of claim 4 wherein thefilaments are arranged on the backing in an amount of at least 10 EPI.13. The tape of claim 4 wherein the filaments are arranged on thebacking in an amount of at least 20 EPI.
 14. A member for use inundersea applications comprising at least one tubular member wrapped ina tape comprising a backing, a layer of corrosion-resistant filaments onone surface of the backing, and pressure-sensitive adhesive layer thatcoats the filaments and binds them to the backing.
 15. The member ofclaim 14 wherein a plurality of conduits are wrapped in an LCPfilament-reinforced tape.
 16. A method for constructing a member forundersea deployment is provided, which comprises: providing at least onetubular member, winding a wire reinforcement about the tubularmember(s); and winding a corrosion-resistant filament-reinforcedmaterial over the wire reinforcement; and coating the filamentreinforced member(s) with a layer of extruded polymer.
 17. The method ofclaim 16 wherein the member(s) is/are conduit(s) and the conduit(s)is/are wrapped with a seawater-resistant filament reinforcedpressure-sensitive tape.
 18. The method of claim 17 wherein thefilaments are selected from the group consisting of E-CR filament, ARglass filament, S glass filament, E glass filament, LCP filament, aramidfilament, UHMW polyethylene or polypropylene filaments, carbon filament,coated filament, and combinations thereof.
 19. The method of claim 18wherein the filament is an LCP filament.
 20. The method of claim 19wherein the LCP filament is a filament of polyester of2-naphthalene-6-carboxylic acid and 4-hydroxy benzoic acid.
 21. Themethod of claim 16 wherein the member(s) is/are conduit(s) and theconduit(s) is/are wrapped with a seawater-resistant filament reinforcedfabric.